EnableMiddleClickScrolling does not exist in ScrollViewerExtensions

### Describe the bug

Cannot found property in ScrollViewerExtensions

### Steps to reproduce

```text
1. Add package CommunityToolkit.WinUI.Extensions
2. Try to use ScrollViewerExtensions.EnableMiddleClickScrolling as descripted by the Windows Community Toolkit gallery.
3. EnableMiddleClickScrolling does not exist.
```

### Expected behavior

Allow me to use this extension

### Screenshots

_No response_

### Code Platform

- [ ] UWP
- [X] WinAppSDK / WinUI 3
- [ ] Web Assembly (WASM)
- [ ] Android
- [ ] iOS
- [ ] MacOS
- [ ] Linux / GTK

### Windows Build Number

- [X] Windows 10 1809 (Build 17763)
- [X] Windows 10 1903 (Build 18362)
- [X] Windows 10 1909 (Build 18363)
- [X] Windows 10 2004 (Build 19041)
- [X] Windows 10 20H2 (Build 19042)
- [X] Windows 10 21H1 (Build 19043)
- [X] Windows 10 21H2 (Build 19044)
- [X] Windows 10 22H2 (Build 19045)
- [X] Windows 11 21H2 (Build 22000)
- [ ] Other (specify)

### Other Windows Build number

_No response_

### App minimum and target SDK version

- [X] Windows 10, version 1809 (Build 17763)
- [ ] Windows 10, version 1903 (Build 18362)
- [ ] Windows 10, version 1909 (Build 18363)
- [ ] Windows 10, version 2004 (Build 19041)
- [ ] Windows 10, version 2104 (Build 20348)
- [ ] Windows 11, version 22H2 (Build 22000)
- [ ] Other (specify)

### Other SDK version

_No response_

### Visual Studio Version

_No response_

### Visual Studio Build Number

_No response_

### Device form factor

Desktop

### Additional context

_No response_

### Help us help you

No, I'm unable to contribute a solution.

Beginne damit, ScrollViewerExtensions im Paket CommunityToolkit.WinUI.Extensions zu finden, und vergleiche seine verfügbaren Member mit der Dokumentation der Windows Community Toolkit gallery. Bestätige das erwartete WinAppSDK/WinUI 3-Verhalten und überprüfe anschließend, dass EnableMiddleClickScrolling im angegebenen unterstützten Windows SDK-Bereich verfügbar und verwendbar ist.

Vom Indexierungsmodell aus dem Issue-Text verfasst.